Overview
Video sensors have proven advantages over loop detectors for various applications beyond the mere measurement of traffic variables, e.g. for incident detection. For the further deployment of traffic sensors, it is important to test their efficiency for specific surveillance and control tasks of practical importance, and to compare with loop-based efficiency. The use and full exploitation of video-based information calls for suitable modifications or even complete re-design of available loop-based surveillance or control algorithms along with field application, demonstration, and comparative evaluation. The innovation of RHYTHM lies exactly in this design and field evaluation of algorithms while comparing results of both detection technologies.
One of the basic tasks of every motorway-network Traffic Control Centre (TCC) is to provide accurate descriptions of the current traffic conditions inside the network. In order for this task to be accomplished, a number of sensors such as magnetic loop detectors, video cameras, floating cars, etc., provide data to the TCC, which are used for traffic surveillance and control purposes. Appropriate algorithms for state estimation/prediction, travel time estimation/prediction, queue-tail tracking, incident detection, and traffic control are subsequently employed for comprehensive surveillance and control of the network traffic flow.
RHYTHM aims at developing new algorithms, or modifying already existing ones, for traffic surveillance and control that use video-based data and rigorously compare them with algorithms that use data obtained by use of loop detectors. Video sensors have proved advantages over traditional loop detectors for various specific applications beyond the mere measurement of traffic variables, e.g. for incident detection. For the further deployment of traffic sensors, however, it is important to test their efficiency for further specific surveillance and control tasks of practical importance, and to compare with loop-based efficiency. As a matter of fact, the use and full exploitation of video-based information calls for suitable modifications or even for complete re-design of available loop-based surveillance or control algorithms along with field application, demonstration, and comparative evaluation.
RHYTHM focuses on four tasks in the domain of traffic management Surveillance:
- Traffic state estimation / prediction
- Queue tail tracking
- Travel-time estimation / prediction Control:
- Isolated traffic-responsive ramp metering
The final objective is to have an algorithm prototype for these 4 tasks. The algorithm will be developed at the Dynamic Systems and Simulation Laboratory of the Technical University of Crete and will be evaluated by use of microscopic simulation, as well as by field implementation in two sites: the A 92 and A 94 ring roads in Munich.
Funding
Results
The quality of the results obtained critically depends on the amount and quality of data used, the kind of sensors installed, and the performance of the specific algorithms employed. Two technically different but operationally complementary ways of collecting data from the road network for traffic surveillance and control purposes are by use of inductive loop detectors on the one hand and video cameras on the other. Loop detectors are placed below the pavement and provide point measurements of flow, speed, and/or occupancy (depending on the specific type of sensor), while video cameras provide space information on the traffic conditions for a section of the road monitored by one or more cameras.
Technical Implications
Loop detectors consist of one or more loops of wire embedded in the pavement and connected to a control box, activated by a signal ranging in frequency from 10 KHz to 200 KHz. They are used to supply data on vehicle passage, presence, count and occupancy. Video sensors send live information to a control centre. For example, if an accident occurs, the data is sent in real time, which allows for a quicker response, decreasing the wait on the road as well as the resulting congestion.